The present invention relates to irrigation sprinklers, and more particularly, to an irrigation sprinkler which combines a pop-up rotor-type sprinkler into a subterranean outer cylindrical mounting case having a protective cover plate.
Sprinklers that eject a stream of water that is slowly rotated over an adjustable arc are widely used to irrigate lawns, golf courses and playing fields. One form of such sprinkler that has been used for decades is the impact drive sprinkler. It includes a sprinkler body with an inclined nozzle for ejecting a stream of water. An oscillating impact arm has a reaction member which is repeatedly deflected laterally away from the stream of water and then biased back against the stream by a spring. The angular momentum imparted by the impact arm rotates the sprinkler body in increments. To effect part circle operation, the impact drive sprinkler includes a reversing mechanism including a trip arm pivotally mounted on the sprinkler body by a pivot pin and coupled by an over-center spring to a reversing arm also pivotally mounted to the sprinkler body by another pivot pin. The trip arm and the reversing arm are coupled together by the over-center spring in such a manner that the trip arm and the reversing arm are each moveable between two stable positions. The spring acts to hold the trip arm and the reversing arm in one or the other of their two stable positions. Movement of the trip arm and the reversing arm between their stable positions is effected by means of a trip extension which depends downwardly from the trip arm to engage adjustable trip stops disposed about the upper portion of a cylindrical support sleeve.
One version of an impact drive sprinkler which has been widely commercialized is disclosed in U.S. Pat. No. 4,182,494 granted Jan. 8, 1980 to Wichman et al. The impact drive sprinkler is mounted on a riser assembly and upon the application of water pressure rises up out of an upwardly opening subterranean cylindrical mounting case whose upper edge terminates at ground level. A disk-shaped protective cover plate is rotatably mounted to the top of the impact drive sprinkler. When the riser and the impact drive sprinkler are retracted into the cylindrical mounting case the rim of the cover plate fits within a lip formed in the upper end of the cylindrical mounting case. A supply line is coupled to through the bottom or side wall of the cylindrical mounting case to pressurize the riser with water.
Impact drive sprinklers have the advantage of significant tolerance to dirt and other debris in the water supply. However, they suffer from a number of drawbacks. They are relatively noisy owing to the "tat, tat, tat" and return "flutter" sounds that are generated by the reaction member intercepting the high pressure water stream. Their plastic parts tend to break or wear out because of the repeated impacts required to provide the driving force. In addition, the arc adjustment springs often slip so the originally set arc or sector is not maintained. For these reasons, impact drive sprinklers have been largely supplanted in new installations by pop-up rotor-type sprinklers that have turbines that drive nozzles through precisely defined arcs. These pop-up rotor-type sprinklers are relatively quiet and can uniformly distribute a precise amount of water over a carefully controlled arc. Rotor-type sprinklers are much more compact than impact drive sprinklers mounted in subterranean cases and require less maintenance.
Many of the impact drive sprinklers mounted in a subterranean cylindrical mounting case, such as those illustrated in U.S. Pat. No. 4,182,494, have been installed and operating for many years and are reaching the ends of their useful lives. The custom has been to replace the worn out impact drive sprinkler with a new impact drive sprinkler in the same subterranean cylindrical mounting case. Landscape maintenance personnel would prefer the advantages of replacing the impact drive sprinkler with a modern pop-up rotor-type sprinkler in order to gain all of its performance and reliability attributes. However, the substantial effort required to dig out the subterranean cylindrical mounting case that houses the impact driver sprinkler and install the required fittings and fixed riser segments to connect and mount a rotor-type sprinkler at grade level has not made this an attractive alternative.
It would therefore be desirable to provide a way to retrofit the millions of units of subterranean impact drive sprinklers "in a can" with modern pop-up rotor type sprinklers. However, a pop-up rotor-type sprinkler is adapted to couple directly to a male fitting on a supply line and is not adapted to couple to the subterranean cylindrical mounting case shown in U.S. Pat. No. 4,182,494. Furthermore, a pop-up rotor-type sprinkler would permanently extend far above grade level if a direct coupling between the lower end of the rotor-type sprinkler and the cylindrical mounting case could be made. This would be entirely unacceptable as the sprinkler could then be tripped over and would be an obstacle to play. In addition, there would be a large uncovered gap between the pop-up rotor-type sprinkler and the side wall of the subterranean cylindrical mounting case since pop-up rotor-type sprinklers do not have any protective disk-shaped cover plate.